The present invention relates to testing apparatus and methods in general, and more particularly to improvements in methods and apparatus for testing cigarettes, cigars, cigarillos, cheroots, filter rod sections and analogous rod-shaped articles which constitute or form part of smokers' products. Still more particularly, the invention relates to improvements in methods and apparatus for simultaneous testing of groups or arrays of parallel rod-shaped articles.
It is well known to monitor the contents of partly finished or sealed packs containing groups of parallel cigarettes or other smokers' products, or to test groups of such products prior to introduction into packs or analogous containers. The purpose of testing is or can be manifold, i.e., to ascertain the presence or absence of a requisite number of products, to ascertain whether or not the products are properly arrayed, to ascertain whether or not the ends of the products are sufficiently or overly dense, to ascertain whether or not the ends of the products carry particles of foreign matter (e.g., fragments of tobacco shreds on filter plugs), whether or not the ends of the products are properly recessed and/or a combination of such parameters. For example, filter cigarettes which are about to be introduced into soft or hinge-lid packs are admitted into the magazine of a packing machine, arrayed in groups containing predetermined numbers of filter cigarettes (e.g., in arrays of twenty including a median row or layer of six filter cigarettes and two outer rows or layers of seven filter cigarettes each, with the articles of the median row staggered relative to those in the outer rows to constitute so-called quincunx formations), introduced into hollow mandrels, and confined in packs which are built around the mandrels. Prior to sealing of both ends of a freshly formed pack, the array of cigarettes is expelled from the respective mandrel to thereby strip the pack off the mandrel, whereupon the still open end of the pack is closed and sealed, e.g., by the application of a revenue stamp or label. Testing of arrays or groups of filter cigarettes normally takes place during transport of filled mandrels to the locus of application of the first or innermost envelope, e.g., a layer of metallic foil. During such transport, the tobacco-containing ends of filter cigarettes are accessible at one open end, and the filter plugs of the articles are accessible at the other open end of the mandrel. This enables suitable testing instrumentalities (such as photocells, movable pins or the like) which are adjacent to the path of movement of the mandrels to monitor the respective end portions of successive groups of filter cigarettes and to generate signals which are thereupon evaluated and processed to effect segregation of defective groups from satisfactory groups.
A drawback of presently known apparatus for the testing of groups of filter cigarettes or analogous rod-shaped articles of the tobacco processing industry is that they are overly complex, unreliable, too sensitive, not suited for testing beyond a certain frequency and/or too bulky for installation in the space which is available in or next to a making or processing machine in a cigarette manufacturing or like plant. Moreover, certain presently known testing apparatus are incapable of simultaneously monitoring two or more different characteristics of successive groups of products so that several apparatus must be installed in series in order to ascertain individual characteristics of successive groups which are caused to advance therealong.
German Offenlegungsschrift No. 28 13 866 discloses an apparatus which can be used for detection of loose ends and for detection of the absence of cigarettes in groups corresponding to those in a cigarette pack or the like. The apparatus employs a discrete bundle of fiber optics sensors for each and every article of a group. All of the bundles (i.e., normally twenty of them when the groups constitute customary arrays of twenty cigarettes each) can receive light from a common source. A drawback of such apparatus is the high number of bundles it must employ. This publication further discloses that the fiber optics of each bundle can include two sections one of which directs light against the ends of articles to be tested and the other of which receives reflected light. The arrangement may be such that one section of each bundle surrounds the other section or that the two sections form a pair of elongated parallel rectangles. In either event, a discrete bundle is needed for each and every article of a group to be tested. This means that, if the apparatus of this German publication were designed for simultaneous testing of both ends of each of a group of twenty arrayed plain cigarettes which are about to be packed, the apparatus would require a total of forty fiber bundles or, otherwise stated, twice as many fiber optics bundles as the number of plain cigarettes in a group. Such apparatus would necessitate the utilization of a highly complex evaluating circuit which would contribute significantly to the initial and maintenance cost as well as to proneness of the control system to malfunction.
German Offenlegungsschrift No. 22 36 218 discloses an apparatus for the testing of successive cigarettes of a layer or row of cigarettes which are transported sideways from a maker to a packing machine. The apparatus employs a so-called bifurcated or branched fiber optics bundle with a random mix of fibers adjacent to the path of one end of each of a series of successive cigarettes. One branch receives light from a suitable source and the other branch transmits light, which is reflected by successive cigarettes, to a photocell which transmits signals to a bridge circuit serving to evaluate the signals and to activate an ejector when the incoming signals denote the detection of defective cigarettes. If such apparatus were to be converted for the testing of groups of cigarettes in a packing machine, its random mix of fibers would have to be designed to assume a shape conforming to that of the ends of all cigarettes in a group and the groups would have to be arrested in positions of alignment with the random mix of fibers. This would entail a slowdown of the packing machine. Furthermore, it would be impossible to pinpoint the defective articles of a group and/or the general positions of defective articles, i.e., whether in an outer row or in a median row, so that the detection of defective articles would be of no help in attempting to localize or pinpoint the cause or causes of defects.
A drawback which is common to each of the aforediscussed prior apparatus is that the configuration of each bundle of optical fibers approximates or equals the shape of the end of an article which is to be tested. In most instances (such as in the apparatus of the German Offenlegungsschrift No. 22 36 218), the cross-sectional area of that end of the bundle which is adjacent to the path of cylindrical articles to be tested has a circular outline. The other German publication discloses the aforediscussed sections one of which surrounds the other and constitutes an annulus having an outer diameter matching or approximating that of the article to be tested, or two elongated parallel rectangular sections whose length matches or closely approximates the diameter of an article.
Another drawback which is common to heretofore known apparatus is that progressive contamination of lenses, mirrors and/or other optical elements which are used therein entails a continuous reduction of accuracy with which the apparatus ascertain the condition of the articles to be tested. Therefore, the machine employing the testing apparatus must be arrested at frequent intervals in order to remove from the optical elements tobacco dust and/or other contaminants which interfere with the generation of reliable signals and prevent the evaluating circuit or circuits from indicating the need for or from initiating corrective measures in immediate response to development of a malfunction which causes the production of unsatisfactory articles. In many instances, stoppage of the machine is not necessary at all, i.e., the contamination is not sufficiently pronounced to warrant an interruption of the operation and attendant huge losses in output.